Update on this: I ran a few graphic benchmark (like Furmark, Kombuster, etc) and my display would crash within 1 to 10 minutes! So this was never VMware issue. ! I am not a gamer, so I never knew I had this problem. I had played some 4K videos but never encountered any problem.
I removed GT 630 graphic card, and now I am running on built-in intel HD 4000 graphics and all problems have dispeared. No crashesin VMware or anywhere else.
I might try a different card, but I am not sure I even need it. I don't play games, and everything is running just as smoothly (if not better) with built-in graphics. Even 4K vdeos are playing without a problem . And no crashes with VMware with 3D enabled.